Priority is claimed on Japanese Patent Application No. 2007-287862, filed on Nov. 5, 2007, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an inner rotor type brushless motor which has, for example, a rotor and a stator.
2. Description Of The Related Art
Generally, an inner rotor type brushless motor has a stator core fitted into and fixed to a stator case and a rotor rotatably provided with respect to the stator core, and includes permanent magnets at an outer peripheral portion thereof. This stator core includes a plurality of teeth which protrude radially inward. A coil is wound around these teeth. Electric current is supplied to the coil by electrically connecting a winding starting end or a winding finishing end of the coil with lead wires via a wiring substrate. As electric current flows into the coil, an attractive or repulsive force is generated between the rotor and the stator to rotate the rotor.
Meanwhile, the above-described lead wires are connected with the wiring substrate by soldering etc., and run to the outside of the motor. In a case where a tensile stress is acted on the lead wires, the stress reaches a joint portion of the lead wires in the wiring substrate, and it causes disconnection of the lead wire from the wiring substrate. Among this kind of brushless motor, there is one which is provided with a harness guide formed in a fork-like shape in the bracket which covers the stator core, the lead wires are fit in the harness guide, and thermoplastic resin is filled in the bracket so as to ensure the pulling resistance (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2003-199279). Further, there is one in which the lead wires are slackened in the bracket and supported by a grommet with a plate such that the length of the lead wires allow tensile stress, and the slack of the lead wires prevents that the tensile stress reaches a joint portion of the lead wires in the wiring substrate.
In recent years, there has been a demand for a smaller and more lightweight brushless motor.
However, in the above-described brushless motor, since the lead wires are slackened in the bracket and supported by a grommet with a plate such that the length of the lead wires allow tensile stress, the space inside the bracket for the slackened lead wires is needed. Therefore, there is a problem in that the size of the motor becomes large.
Further, if a lead wire is disconnected from the wiring substrate, there is a problem in that short-circuiting is caused by contacting the disconnected lead wire with other lead wires or metal-parts.
Thus, the present invention has been made in view of the above-described circumstances, and the object of the invention is to provide a brushless motor capable of enduring a tensile stress which acts on the lead wires and securing insulation properties while being made small and lightweight.